of steroid hormones in human endometrium by tracer methods involving the perfusion of labeled estradiol, estrone, progesterone and 20 intracellular and intranuclear concentrations of the hormones will be determined. Endogenous levels of the hormones in various types of endometria, saturation values for estradiol. 2) Measurement of 17 beta-hydroxy steroid dehydrogenase activity in proliferative and secretory endometrium to determine the importance of this activity in regulating the levels of estrone and estradiol in human endometrium. 3) Investigation of the uptake of uridine by tissue slices, the intracellular compartmentalization of this compound and the influence of its concentration on the rates of synthesis of nucleic acids. 4) Measurement of the rates of 16 alpha-hydroxylation of dehydroisoandrosterone sulfate in men and evaluation of the effect of estrogens and progesterone on these rates. distribution, transit times and non-steady state of a hormone.